1. Field of the Invention
The application is related to DC-DC converter.
2. Description of the Related Art
FIG. 1 shows a multi-channel power supply circuit arrangement disclosed in Japanese Laid-open Patent Publication No. 2004-23948. An oscillator 100 generates a basic pulse Pbp with an oscillation period that depends on a resistance value of a resistor Rd connected to a soft start setting terminal 300. A counter circuit 210 counts up 4 bit-sized digital signals S1 to S4 by counting a number of the basic pulses Pbp from the oscillator 100. A DA converter 230 converts the digital signals S1 to S4 input from the counter circuit 210 into an analog signal Vs having a resistance divided into sixteen levels, and outputs the analog signal Vs. For this conversion, a series resistance circuit having 16 resistors, R10 to R160, is used. The analog signal Vs is sequentially switched one level at a time in accordance with the 4 bit-sized digital signals S1 to S4, and is outputted as a consecutively rising voltage signal. This enables a soft start operation.
Other art related to a soft start circuit is disclosed in Japanese Laid-open Patent Publications No. 2006-288054, and No. 2004-173386.